Scientists may have found the only green star in the universe. But how? Stars can have many colours. While most people see the sky as white, sometimes the Earth’s atmosphere gives it another colour. Our sun, for example, is actually white. The only reason we see it as yellow is because of the atmospheric scattering: our planet scatters the blue wavelength of sunlight, and this allows the longer yellow, orange, and red wavelengths to reach our eyes. So, its real colour is white, and even if we were outside our planet, we wouldn’t see it like that.
Stars have all the colours: It shows us only what we are capable of comprehending
This happens everywhere. The stars interact with the gravitational field of the planets, and their atmospheres translate the light to other colours – as the sun is white, it has all the colours. Now, a green star is different: it cannot exist. While it’s technically in the spectrum, it might look like some are green, but in reality, it just looks that way during the peak. Not all the time. However, this green star that NASA found is different.
In the Libra constellation, located between Virgo and Scorpius, although the exact location can’t be defined due to the distance of the stars that form the stellar formation. It’s a matter of positioning, not how far it is. In Libra, the brightest star, Zubeneschamali, is exactly the one astronomers are trying to understand why it appears green when it should be white.
The green star myth is unveiled: The reality is very mundane
Zubeneschamali, also known as Beta Librae, is the brightest star in Libra. It edges out Zubenelgenubi by just a little, but for centuries, it has sparked more curiosity. Today, most astronomers say the star looks white or bluish. However, in the past, observers swore it shone green. If that were true, it would be the only naked-eye green star in the entire night sky.
The mystery is that stars do not really appear green. Even if one puts out light strongest in the green range, the yellow and blue wavelengths on either side drown it out. Our eyes blend the colours, and the result is never green. That’s why scientists say we only see stars in shades of red, orange, yellow, white, or blue.
Inside the star’s power: Here’s how Beta Librae shines so brightly.
What we do know: Zubeneschamali is a B8V dwarf, blazing at more than 12,000 K. It burns 130 times brighter than the Sun, nearly five times its size, and more than three times its mass. It spins furiously too, more than 100 times faster than the Sun, reaching 250 km/s. At only 80 million years old, this is still a young star.
Science has given Beta Librae the edge over its rival in Libra, Zubenelgenubi. Astronomers now know the beta star burns much brighter than the alpha. From Earth, though, the two look almost equal. That’s only because Zubenelgenubi is closer — 75 light-years away, while the other one sits at 185. In truth, Zubeneschamali shines nearly five times brighter than Zubenelgenubi, and about 130 times brighter than our Sun. We still don’t know much about why this spot was hidden all this time.
You can spot the stars yourself: Look at the sky during this time
The “green star” is visible during the summer nights in the Northern Hemisphere. It climbs high in the southern sky and is easy to spot. To find it, start with Antares, the bright red heart of Scorpius. From there, move about two fist-widths to the northwest — the star will be there, shining and waiting to be studied (like this one that blew up, and it’s expanding in our galaxy)